In the figure below, a steel bar is sitting on two parallel metal rails connected to each other by a resistor. It is being pulled to the right with a constant force of magnitude F = 1.40 N. The friction between the bar and rails is negligible. The resistance of the resistor is R = 8.00 Ω. The bar is moving at a constant speed of 1.85 m/s. The distance between the rails is d. A uniform magnetic field B is directed into the page.
(a) What is the current through the resistor (in A)? 0.57 A
(b) If the magnitude of the magnetic field is 3.10 T, what is the length d (in m)? 0.79 m
(c) What is the rate at which energy is delivered to the resistor (in W)? 2.59 W
(d) What is the mechanical power delivered by the applied constant force (in W)? 2.59 W
What If? Suppose the magnetic field has an initial value of 3.10 T at time t = 0 and increases at a constant rate of 0.500 T/s. The bar starts at an initial position Xo = 0.100 m to the right of the resistor at t = 0, and again moves at a constant speed of 1.85 m/s. Derive time-varying expressions for the following quantities.
(e) the current through the 8.00 Ω resistor R (Use the following as necessary: t. Assume It) is in A and t is in s. Do not include units in your answer.
I(t)
(f) the magnitude of the applied force F required to keep the bar moving at a constant speed (Use the following as necessary: t. Assume F(t) is in N and t is in s. Do not include units in your answer.)
F(t)